This invention relates to a method for preparation of an absorbent composite having an absorbent polymer firmly fixed to a substrate. More particularly, the invention relates to a method of manufacturing easily and at high productivity an absorbent composite excellent in absorption capacity, outstandingly low in the residual monomer in the absorbent polymer, and superior in safety, in which the absorbent polymer does not drop off the substrate even after absorbing a large quantity of water, a method of manufacturing continuously and at high productivity, a product obtained from these methods, and an apparatus to be used in such methods.
Recently as the means of obtaining absorbent composite by fixing an absorbent polymer to a substrate, various methods of applying a water-soluble monomer which can be converted into an absorbent polymer on a substrate, and then polymerizing have been proposed (for example, the Japanese Official Patent Provisional Publication Nos. 60-149609, 62-243606, 60-151381, and 62-243612). Since the polymerization reaction of water-soluble monomer in such proposed methods is impeded by oxygen and others existing in the air, it is performed in a polymerization-inert atmosphere such as an oven completely replaced by nitrogen gas.
By these known methods, however, when polymerizing the monomer applied on the substrate, it is required to keep the substrate in a specifically determined condition for a long period, and the apparatus for polymerization itself becomes large in size, and the energy loss is significant, and it is not advantageous for manufacturing absorbent composite industrially. Besides, the absorption capacity of the obtained absorbent composite was insufficient, and the amount of the residual monomer was too much.